Add Gravatar support.

Cargo.lock

@@ -1409,6 +1409,12 @@ dependencies = [
  "opaque-debug 0.2.3",
 ]
 
+[[package]]
+name = "md5"
+version = "0.7.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "490cc448043f947bae3cbee9c203358d62dbee0db12107a74be5c30ccfd09771"
+
 [[package]]
 name = "memchr"
 version = "2.3.4"
@@ -2365,7 +2371,7 @@ dependencies = [
 
 [[package]]
 name = "revolt"
-version = "0.3.3"
+version = "0.3.3-alpha.0"
 dependencies = [
  "async-std",
  "async-tungstenite",
@@ -2381,6 +2387,7 @@ dependencies = [
  "lettre",
  "log",
  "many-to-many",
+ "md5",
  "mongodb",
  "num_enum",
  "once_cell",
@@ -2397,6 +2404,7 @@ dependencies = [
  "snafu",
  "time 0.2.25",
  "ulid",
+ "urlencoding",
  "validator",
 ]
 
@@ -3398,6 +3406,12 @@ dependencies = [
  "percent-encoding",
 ]
 
+[[package]]
+name = "urlencoding"
+version = "1.1.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c9232eb53352b4442e40d7900465dfc534e8cb2dc8f18656fcb2ac16112b5593"
+
 [[package]]
 name = "utf-8"
 version = "0.7.5"